1. Field of the Invention
The present invention relates to radiolucent surgical tables and, more particularly, to a radiolucent surgical table with a low radiographic shadow edge profile used to support a patient adjacent x-ray imaging devices such as C-arm scanners, CT, fluoroscopic, and other whole body scanners.
2. Description of the Prior Art
Conventional surgical tables include a flat patient support and a lower base for holding the patient support a predetermined distance from the floor. The base of conventional surgical tables commonly includes control apparatus for tilting the flat patient support through a range of orientations to facilitate performance of certain surgical procedures. Typical flat patient supports are made of surgical stainless steel and in most cases include a set of metal side rails supported along the edges of the table for holding surgical accessories, instrumentation, and the like. Typically, the side rails conform to an industry standard cross sectional size and configuration so that surgical accessories from any vendor source can be directly connected to surgical tables built by another vendor without modification of the attachment interface.
One disadvantage of stainless steel table tops of the type described above is that they block x-rays. Accordingly, their use in surgical or interventional procedures that require x-rays, fluoroscopic or other patient images to be taken are quite limited.
As a result, patient support tables have been proposed that utilize an x-ray translucent material, such as phenolic resins, in selected portions of the table top. The x-ray translucent material allows interoperative x-ray image signals to be generated using fluoroscopic devices, C-arm or CT scanners and other imaging equipment.
One such example of a prior art radiolucent table is shown at FIG. 1. As illustrated in cross section, the flat patient support 10 includes a substantially planar table top member 12 formed of a x-ray translucent material such as, for example, a carbon fiber material or a phenolic resin such as sold under the tradename SPAULDITE. Due mainly to load carrying capacity limitations and to enhance stiffness, the table top 12 is supported on either side by a pair of longitudinally extending metal frame members 14, 16. Each of the metal frame members 14, 16 are attached to the bottom surface of the table top member 12 using a suitable cement such as an epoxy, fasteners, or the like. A pair of side rail members 18, 20 are held in a fixed relationship relative to the metal frame members 14, 16 as illustrated. The side rail members 18, 20 have a size and shape that conform to the industry-wide standards noted above.
One disadvantage of the flat patient support 10 illustrated in FIG. 1 is that the metal frame members 14, 16 as well as the side rail members 18, 20 generate shadows when the patient support 10 is used in radiographic imaging procedures. As a result, only the portion of the radiopaque table top member 12 that is disposed between the pair of metal frame members 14, 16 is usable for radiographic imaging. This limitation becomes more pronounced when the table is tilted relative to the x-ray generator. The angle of the table relative to the x-ray source effectively shortens the distance between the metal side frame members 14, 16 as viewed from the x-ray source thus reducing the shadow-free areas in the radiographic image.
FIG. 2 illustrates another prior art surgical table configuration that is somewhat useful in radiographic imaging and in certain interventional procedures. As shown there, a predominant feature of the flat patient support 22 is a relatively thick slab 24 of radiographic material having a generally rectangular cross section. The slab 24 is provided on opposite transverse edges 26, 28 with a substantially square accessory interface profile 30, 32 as shown. Each of the accessory interface profiles 30, 32 are sized and shaped to receive a pair of accessory coupler members 34, 36 on the opposite transverse edges 26, 28 of the radiolucent slab 24. In turn, each coupler member 34, 36 carries an industry standard side rail member 18, 20 of the type described above. In that way, most commercially available accessories can be used with the table.
One drawback to the “slab” type radiolucent surgical tables shown in FIG. 2 is that the accessory coupler members 34, 36 are typically formed of metal and therefore obstruct x-ray signal propagation through portions of the table along the table edges. As a result, undesirable shadows are formed in the radiographic image.
Simple removal of the accessory coupler members 34 or 36 does not completely solve the shadow problem. The vertical surfaces along the square edges of the accessory interface profiles 30, 32 lead to shadows in radiographic images. The shadows are caused because, during normal use of the table, the vertical edges of the profile are typically aligned in a substantially parallel relationship with x-ray signal propagation. As a result, the edge surfaces tend to attenuate the x-ray signal to a substantial degree greater than the flat horizontal surfaces and, accordingly, the vertical edge surfaces generate shadows in the radiographic image.
It is, therefore, desirable to provide a radiolucent surgical table that presents a substantially uniform attenuation characteristic to x-ray signals in both the lateral and transverse directions and with the table held flat or tilted relative to the x-ray signal source. In that way, the radiographic images of a patient disposed on such surgical table would be free and clear of extraneous shadows.
It is further desirable to provide such a table that, in addition to being substantially x-ray shadow free, provides a surgical accessory interface profile so that a wide range of surgical accessories can be easily and directly connected anywhere along the edge of the table top. Preferably, the accessory interface profile presents a substantially uniform attenuation characteristic to x-rays passing through the table top and table top edges regardless of the angle of the table top relative to the x-ray source.